Process of separating potassium salts from mother-liquor salts.



UNITED STATES PA'rnNT OFFICE.

GIJ'Y STERLING, 0F SALT LAKE CITY, UTAH.

PROCESS OF SEPABATING POTASSIUM SALTS FROM MOTHER-LIQUOR SALTS. I

I0 Drawing.

following is a full, clear, and exact description thereof.

This invention is a novel process of treating mother liquor salts, containing potassium salts in a soluble form, obtained (after crystallizing out as much as practicable of the common salt) from natural brines, such as sea water or water of salt lakes such as Salt Lake, Utah, or of salt wells and springs, to recover such potassium salts.

In addition to a reduced proportion of common salt, such mother liquor salts contain chlorids of magnesium and potassium, and sulfates of sodium, magnesium and potassium; of these the potassium salts form a small proportion and are valuable, but the separation of such potassium salts from the mother liquor salts, by the usual methods of fractional crystallization, is both diflicult and expensive.

In mother liquor salts containing as one ingredient a potassium salt, (such as K,SO, or KCl) the potassium salt is already in a soluble form and there is no necessity for chemically changinlgnits form. But the proportion of potassiu salt contained in such mother liquor salt is so small that unless the potassium salt, in a concentrated or purified condition, can be separated from the mother liquor salts such potassium salts is unavailable for practical use.

It is the object of this invention to obtain from mother liquor salts either pure potassium salts or a mixture of salts relatively rich in potassium salts; or, in other words, to separate from mother liquor salts containing potassium salts the potassium salts alone or relatively free from the other mother liquor salts.

I have discovered that if to mother liquor salts of the character described, silica and limestone are added, and the whole finely powdered, and intimately mixed and heated, preferably with stirring, to about 1400 C, for three or four hours, the whole of the potassium salts and the sodium chlorid contained in the mother liquor salts are sublimed; and at the same time the sodium of Specification of Letters Iatent.

ake and three hours, preferably Patented Apr. so, 1913.

Application filed September 17, 1917. Serial No. is.

the sodium sulfate, and the magnesium of the magnesium chlorid and of the magma sium sulfate, Sif contained 1n the mother liquor salts,) a 'ong with the calcium of the limestone, combines with the silica to form a sodium-calcium-magnesiuxmsilicate.

For example, such mother liquor salts would contain,

Sodium chlorid :NaCl (common salt), Sodium sulfate =Na.,SO,, Magnesium chlorid=M C1,,

Potassium chlorid =Kfil.

When such mother liquor salts are mixed with silica and limestone in pro er proportions pulverized and properlyheated m a suitalole furnace, as stated, the sodium of the sodium sulfate, the magnesium of the magnesium chlor 1d and the calcium of the limestone will combine chemically with the silica, forming a sodium-calcium-ma esium-sili cute and at the same time ,the Cl; NaCl, the SO, magnesium chlorid and the 00 of the limestone, separate from the residue; the KCl \and NaCl in sublimed form, and the S0,: (+SO O), the C1 and CO in gaseous form.

The sublimed KCl and NaCl are separated and precipitated from the gases by suitable means and ved. Thus I obtain a mixture of K61 and 2101 which, as compared to the mother li uor salts, is relatively rich in otassium sa ts, and from this mixture of l Cl and NaCl it is relatively easier and economically practicable to separate the K01 by ordinary methods of fractional crystalli zation.

One practical. mode of carrying out my process is to take about 0.8 parts by Weight of such mother liquor salts, 0.50 parts of of the sodium sulfate, the C1,, of the silica (or any rock containing an equivalent amount of silica) and 0.85 parts of limestone, thoroughl comminute and intimately mix them, and t en heat the mass in a suitable furnace to a temperature of approximately 1400 degrees C. for a riod of about mec anically stirring the mass While sub'ected to the heat, then condensing by suita 1e means the sublimed salts producing a mixture of potassium salts and sodium chlorid relatively rich in potassium salts and free from magnesium saglts or sodium Silltslflllel' than sodium chlo- I'l Any suitable mechanical apparatus may be employed in carrying out the process.

form, all of the potassium salts and the so:

dium chlorid; and by condensing the suhlime-d salts I obtain a mixture of potassium salts and sodium chin-id (relatively rich inpotassium salts and free from sodium sul fate and magnesium salts) which may be used directly in the manufacture of i ertilizcrs or from which the potassium salts may, at relatively small expense, in ip:irated in the usual or preferred manner.

In this process the silica is the cssential reagent, acting as a nucleus with which the SOClillIIl, calcium and magnesium combine. \Vithout the silica, there would he no reaction. The limestone is used because, under the proportions and conditions stated, it re terds the chemical combination of the potasslum with the silica, and at the same time in duces the sublimation of the potassium salts before they are decomposed by the silica.

If the mother liquor salts and silica, without limestone, were heated to the point of reaction there would be formed a pi'itassiumsodium-magncsium-silirate. and a large partif not allof the potassium contained in the salts would go into chemical combination with the silica and bECOIYli unavailable, in spite of the fact that potassium salts are {.g'encl'allp more easily suhlimcd than. most sodium salts.

' It is course, obvious that a. natural silicatc, whether containing potassium or not, may (on account of its contained silica) Inc used instead of pure silica.

I claim:

1. The process of extracting potassium salts from mother liquor salts obtained from salt brines, consisting in mixing mother liquor salt, silica and limestone, and heating same until the magnesium and the sodium of the sodium sulfate contained in the mother liquor salts and the calcium of the limestone chemically combine with the silica, subliming the potassium salts and the sodium chlorid, and condensing the suhlimcd salts, producing a mixture relatively rich in potassium salts.

2. The process of extracting potassium salts from mother liquor salts obtained from salt brincs, consisting in heating, with stirring. a suitahly proportioned, finely powdered and intimately mixed mixture of mother liquor salt, silica and limestone; until the magnesium and the sodium of the sodium sulfate contained in the mother liquor salts and the calcium of the limosione chemically combine with the silica; suhliming the potassium salts and the so dium chloridg and condensing by suitahh means the sublinicd salts preducing a miX- ture rclal ively rich in potassium salts.

1%. Elm process of extracting potassium salts from mother liquor salts obtained from salt hrincs, consisting in heating, with stir ring. a suitably proportioned, finely ground and intimately mixed mixture of mother liquor salt, a silicate and limestone, combining chemically the magnesium and the sodium of the sodium sulfate contained in the mother liquor salts with the silicate, sublim ing the potassium salts and that part of the sodium salts remaining uncoinbined with the silicate, condensing by suitable means the snhlimed salts, producing a mixture of pr tassium and sodium salts relatively rich in potassium salts free from magnesium sells.

1. The process of extracting potassium salts from mother liquor salts obtained from salt brines, consisting in heating, with stirring, a suitably proportioned, finely ground and intinmtely mixed mixture of mother liquor salt, a potassium bearin silicate and limestone, combining chcmicaly the mag ncsium and the sodium of the sodium sulfate contained in the mother liquor salt, subliming the potassium salts and that part of the sodium salts remaining nncombined with the. silicate, converting the insoluble potassium of the silicate into a soluble potassium salt, sublimin also the latter, and condensing by suitab e means the sublimed salts, thereby producing a mixture of potassium and so dium salts relatively rich in potassium salts and free from magnesium salts.

In testimony that I claim the foregoing as my own, I allix my signature.

' GUY STERLING. 

